TOSHIBA 37CV505D TV turns on and then off

[Ukdigger]

TOSHIBA 37CV505D TV
POWER SUPPLY PE0531 V28A000711B1

TV turns on with no backlight and then off after about 10 seconds
All caps test good with ESR meter, no signs of any burning, board has been repaired before but not by me. Should I be getting 12v on pin 1 and 2 12vlcd
Any help would be welcome.

[dskall]

Re: TOSHIBA 37CV505D TV turns on and then off

Do backlights flash? Are you getting an image on screen?

[nomoresonys]

Re: TOSHIBA 37CV505D TV turns on and then off

The first thing I do when a tv goes on and off is check for bulged or leaking capacitors, they don't have to look bad to be bad tho. Second is in signature below, which is pretty simple and low cost, just to make sure it isn't the problem.

[Ukdigger]

Re: TOSHIBA 37CV505D TV turns on and then off

I don't see the screen flash from the front, in a dark room, but I can see a flash looking from the back near the underside of the inverter board.

[vinceroger69]

Re: TOSHIBA 37CV505D TV turns on and then off

This is a older ccfl lit tv i wonder if this has the two second to black fault which is sometimes caused by the invertor or a failed ccfl tube or connection.
Not sure if you should have the 12volts on psu your missing, i would hope a more experienced member who understands schematics will advise on that.

[dskall]

Re: TOSHIBA 37CV505D TV turns on and then off

I don't see the screen flash from the front, in a dark room, but I can see a flash looking from the back near the underside of the inverter board.

A flash as in an arc?

[Ukdigger]

Re: TOSHIBA 37CV505D TV turns on and then off

No, a very brief flash of the ccfl's

[nomoresonys]

Re: TOSHIBA 37CV505D TV turns on and then off

How bout a picture of the whole back of tv, if there's a cover on the inverter board take it off before the picture, check the fuse on inverter F1.

[Ukdigger]

Re: TOSHIBA 37CV505D TV turns on and then off

The fuse F1 is good and the caps esr is 0.0002 and 0.0007 (inverter board)

[nomoresonys]

Re: TOSHIBA 37CV505D TV turns on and then off

The ribbon cable with the blue end looks really crooked.

[vinceroger69]

Re: TOSHIBA 37CV505D TV turns on and then off

do both of the invertor transormers measure the same resistace as they do fail.
Service manual link

[lotas]

Re: TOSHIBA 37CV505D TV turns on and then off

Check the PFC in the power supply, what voltage you have on a large capacitor, in operating mode it should rise
up to DC 380v - 390v.

[dskall]

Re: TOSHIBA 37CV505D TV turns on and then off

No, a very brief flash of the ccfl's

And you don't smell any ozone? ccfl's are high voltage and prone to bad connections and arcing.

[Ukdigger]

Re: TOSHIBA 37CV505D TV turns on and then off

Reseating the crooked cable made no difference.
Before I go any further, I'm not getting any reading on this cap 4kv 22j 70

[nomoresonys]

Re: TOSHIBA 37CV505D TV turns on and then off

Read it in ohms if you didn't, it is labeled starting with a Cxx?

[Ukdigger]

Re: TOSHIBA 37CV505D TV turns on and then off

I got 10.3 in the 20k scale

[nomoresonys]

Re: TOSHIBA 37CV505D TV turns on and then off

Don't seem bad, what do you get on 200 ohm setting?

[Ukdigger]

Re: TOSHIBA 37CV505D TV turns on and then off

nothing on 200 or 2k

[nomoresonys]

Re: TOSHIBA 37CV505D TV turns on and then off

You know, I forgot what they should be, let me see if I have one to measure.

[diif]

Re: TOSHIBA 37CV505D TV turns on and then off

Reseating the crooked cable made no difference.
Before I go any further, I'm not getting any reading on this cap 4kv 22j 70

Check the four mosfets on the inverter for shorts.